feat: 更多的 HTTP / ASGI 组件

[RF-Tar-Railt]

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@copilot Summarize pull request content

[Copilot]

@copilot Summarize pull request content

This PR adds expanded HTTP client and ASGI server support to the Amnesia framework across 8 commits (+2374/-475 lines, 23 files changed):

HTTP Client Layer (builtins/http/)

• Generic HTTP types (httptypes.py, 456 lines): Library-agnostic Request/Response models with headers, cookies, multipart, JSON, streaming support, and type aliases (HeadersType, QueryType, FormDataType, etc.).
• Base class (base.py): Abstract HttpClientService extending launart.Service with a unified request() interface.
• 4 client implementations, each wrapping a different library into the common interface:
  • aiohttp — AiohttpClientService
  • httpx — HttpxClientService
  • niquests — NiquestsClientService
  • pyreqwest — PyReqwestClientService
• Auto-discovery (__init__.py): Lazy imports with helpful error messages, plus a top-level request() helper that auto-selects whichever HTTP client is installed and registered with Launart.

ASGI Server Layer (builtins/asgi/)

• Granian support (granian.py, 120 lines): New GranianASGIService with GranianOptions dataclass for the Granian ASGI server.
• Refactored existing Uvicorn and Hypercorn services (simplified by ~130 lines combined).
• Lazy __init__.py: Unified import pattern with graceful ImportError handling for all three ASGI servers.

Other

• New optional dependencies in pyproject.toml (niquests, pyreqwest_impersonate, granian).
• Example scripts (exam_aio.py, exam_granian.py, exam_uvicorn.py) and pre-commit config update.